THE BEHAVIOR OF A PARASITIC COPEPOD 59 



XII. SUMMARY 



i. Lernaeopoda edwardsii is a parasitic copepod which at- 

 taches itself to the gills of the brook trout. It attacks this 

 species of trout only, the rainbow as well as the German-brown 

 trout being immune from it. Undoubtedly, its reaction to the 

 brook trout is a chemotactic one. 



2. The free-swimming existence of the organism is very short, 

 about two days at the most, and during this stage of its life 

 history it swims about with a darting spiral motion. 



3. When the copepod stops moving through the water, it 

 sinks to the bottom in an upright position, with its head down. 

 When it strikes bottom it may rest either on its ventral or 

 dorsal side, depending entirely on which side of the animal 

 strikes the bottom first. Undoubtedly the organism sinks 

 because its specific gravity is greater than that of water. 



4. Lernaeopoda is strongly positive in its reactions to intense 

 light. In light of low intensity, however, it is indifferent. 

 Because of its affinity for strong light, the copepod moves about 

 near the surface of the water during most of the day. At night, 

 the animal remains indifferent to weak light, and through its 

 specific gravity it sinks to deeper waters. 



5. Increasing the temperature of the water does not change 

 the behavior of the organism to light. 



6. Some chemicals have little effect on the behavior of Ler- 

 naepodao edwardsii to light. No reversal in the positive be- 

 havior of the larva could be induced through the use of sodium 

 chloride, potassium chlorate, copper sulphate, calcium chloride, 

 hydrochloric, sulphuric, tartaric and oxalic acids. In hydrogen 

 peroxide, magnesium sulphate, nitric and acetic acids indica- 

 tions of reversal were noticeable. 



